Vibratory classification screen with means for dampening vibrations



March 25, 1958 J. w. WANTLING 2,328,014

VIBRATORY CLASSIFICATION SCREEN WITH MEANS FOR DAMPENING VIBRATIONS Filed April 27, 1954 s Sheet-Sheet 1 I INVENTOR JflffiJlf/W g} ATTORNEYS March 25, 1958 J. w. WANTLING 2,328,014

VIBRATORY CLASSIFICATION SCREEN WITH MEANS 7 FOR DAMPENING VIBRATIONS Filed April 27, 1954 5 Sheets-Sheet 2 1 INVENTOR Ila-i I away/11, i5 5 BY Want ATTQRNEYS 1958 J. w. WANTLING VIBRA'I'ORY CLASSIFICATION SCREEN WITH MEANS FOR DAMPENING VIBRA'IIONS Filed April 27, 1954 J WW BY v

ATTORNEYS United States Patent 'VIBRATORY CLASSIFICATION SCREEN WIT H MEANS FOR DAMPENING VIBRATIONS Joseph W. Wantling, Bluefield, W. Va.

Application April 27, 1954, Serial No. 425,886

3 Claims. (Cl. 209-326) This invention relates to a vibratory screen assembly of that type in which alive frame embodying the screen is floatably'supported, as by springs, upon a fixed base frame, and caused to vibrate through the rotation of an eccentrically weighted driven shaft carried by the live frame. Such assemblages are useful in screening continuously supplied streams of coal, for example, and in the classificationof various grannular materials.

One of the objects of the invention is to provide apparatus .of the type described, having dual eccentrically weighted driven shafts the relative displacement of which can .be adjustably changed so as to bringthe offset weights into various phase relationships for adjusting the vibratory intensity or amplitude according to the nature of the material being handled or the results desired.

Another object of the invention is the provision in a vibratory screen assembly, as described, of a vibratory head which houses the eccentrically weighted shafts, and provides for adjusting the relative displacement thereof by altering the relative phase of the intermeshing gears by which they are driven, the gears being readily disconnectable from said shafts to facilitate this adjustment.

Still another object of the invention is the provision of the vibratory head as described, in which the vibration generating shafts are carried in freely rotatable annular bearings mounted in the end walls of said head, the hearings on the side adjacent the driving gears being in part retained by the hubs of said gears, the latter being wedgingly held fast to said shafts through the intermediary of tapered bushings, and being quickly removable to facilitate the removal of said bearings, by the release of said bushings.

A further object ofithe invention is the novel mounting of the axially parallel vibration generating shafts in the spaced parallel end walls of the vibratory head, in

freely revoluble annular bearings, said mounting including inner and outer annular bearing seats, the former comprising cylindrical bushings on the ends of the shafts so arranged as to provide clearance between the inner seats and hearings to allow for thermal elongation of the shafts.

Another object of the-invention is the provision of a vibration control member which permits unrestrained vibration of the vibratory unit throughout normal ranges, butdampens excessive vibrations.

Other objects .of the invention will appear as the following description of a practical embodiment thereof proceeds.

In the drawings which accompanyand form a part of the following specification, and throughout the figures of which the same reference characters have been used to denote identical parts:

Figure l is .a view .in side elevation of a vibratory screen assembly embodying the principles of .the invention;

Figure'Z is alongitudinalintermediate vertical section through the vibratory head showing the far wall of the live frame;

Figure 3 is a left end view in elevation of the apparatus shown in Figure 1;

Figure 4 is a sectional view through the vibratory head, taken along the line 4-4 of Figure 1;

Figure 5 is a plan view, partly in section, of one of the automatic friction bumpers;

Figure 6 is an end elevation of the bumper shown in Figure 5;

Figure 7 is a vertical section taken through the axis of one of the bumper cups.

Referring now in detail to the several figures, the numeral 1 represents the vibratory screen assembly as a whole, which comprises a fixed frame 2 and a live frame .3, the latter being spring-supported on the fixed frame.

The fixed frame comprises, in the specific embodiment shown, a pair of spaced parallel I beams 4, which may be connected at their ends and intermediately by the transverse bars 5, welded at their ends to said I beams.

Mounted on the I beams 4 are the longitudinally spaced pairs of transversely disposed bolsters 6, each consisting of a section of an I beam having its lower flange 7 resting upon one of the I beams 4, being welded thereto, and having a series of three spring retaining bosses 8, arranged longitudinally on its top flange 9 in fixed relation thereto.

The vibration control mechanism is built into the bolsters 6, comprising a cylindrical bumper block cup 10, best shown in Figures 5, 6, and 7, which extends through the web 11 of the I beam 4 perpendicular thereto, being welded to said web, the rear and front port-ions of said cup being additionally supported by plates 12 and 13 on opposite sides of the web 11, spaced therefrom and parallel thereto. Said cup extends through said plates, being welded thereto. The bumper block cup is open at the end adjacent the live frame, the opposite or outer end being closed with the exception of a central threaded aperture in which a bolt 14 screws, having a lock nut 15. The inner end of the bolt presses the center of a follower disk 16. A cylindrical rubber bumper block 17 rests against the follower. It is preferably of two diameters, the inner part 18 which seats against the follower being a friction fit within the cup lihand the outer, part being of somewhat smaller diameter to establish an annular clearance space 20 within the cup about said pad. The pad has the elastic and deformable qualities inherent in rubber. It projects beyond the open end of the cup and its function and mode of operation will be explained in due course.

The live frame 3 is formed as a box having deep parallel sides 21 rigidly connected by a series of transverse horizontal bars 22 at an intermediate level in their height, and two downwardly convergent series of transverse horizontal bars 23, all of said bars being welded to the sides of said live frame. The horizontal series supports a screen 24, having shallow sides 25 and a perforate bottom 26, said screen being fixed with respect to said sides. The convergent series of bars 23 are beneath the screen 24 and support chutes 27, which are inclined downwardly and spaced apart to receive and discharge fines or other small material which passes through said screen.

The live frame is of such width as to lie within the upward projection of the I beams 4 which constitute the sides of the fixed frame. Directly above the bolsters 6 are the brackets 28. These are of similar construction, each comprising a base plate 29 having a barrel bearing 30 arranged transversely thereacross on its opposite face, buttressed bythe triangular gusset plates 31. Said base plate, bearing, and gusset plates are welded to form an integral unit. On its under side the base plate 25 has three spring retaining bosses 32 complementary to the similar bosses 8 on the top of the corresponding bolster. The brackets 28 are pivotally mounted on sturdy pins 33 .live frame.

with their ends surrounding the bosses'S and'cornplementary bosses .32, and retained thereby. 1 7 ..1

i The vibratoryhead is mounted transversely of the It comprises a spaced pair of side walls 36 and 37 secured to the top marginsof the side walls of the live frame in transverse congruency. Said side wallssupport a pair of coaxial bearings 38 and a second pair of similar coaxial bearings 39, in which are journaled the ends of shafts and 41. Said shafts have fixed to one end of each, the intermeshing gears 42 and 43, by means of which'the shafts are'driven together and in the oppo site direction. The shaft 41 is provided with a pulley 44, fixed to its opposite end and by mean of which the shafts 40 and 41 are driven by an electric motor or other source of power, not shown. The shafts each carry an eccentric weight 45 and 46, and it is these weights which, due to the rotation of the shaft, produce the vibration which is transmitted to the live frame. For the sake of safety, a pair of cylindrical tubular housings 47 surround the orbits of the weights 45 and 46 and are welded or otherwise fixed to the side walls 36 and 37. The weights are out of contact with the housings The shafts 4t) and 41 are preferably driven to rotate in opposite directions, and therefore, no idler is employed between the gears 42 and :3. It is desirable to be able to change the nature and amplitude of the vibrations of the apparatus for various materials, and this may be done in a simple manner by changing the phase of displacement of the gears.

This adjustment is facilitated by tapering the bores of the gears in an outward direction and. providing a' complementary tapered bushing 48 for each of the gears, said bushings fitting upon the respective shafts and externally fitting within the bores of the gears. A push plate 49 abuts the outer end of the bushing, being centrally perforated for the introduction of a bolt 50, which screws into an axial bore in the adjacent end of the corresponding shaft. By tightening the bolt, the push plate 49 forces the bushing 48 wedgingly into the associated gear, securing it firmly to its'shaft, the frictional pressure of the push plate against the end of the bushing holding the latter fast to the shaft. The gears are readily loosened by slightly unscrewing either of the bolts 50. This permits the bushing, together with the gear, to slide out on the end of the shaft a sufficient distance to permit the gear to be rotated to a new position of displacement. The bolt fail is again tightened,'drawing the tapered bushing up into fast engagement with the gear.

. By varying the relative angularpositions of the eccentric weights 45 and 46, the nature and amplitude of the vibrations imparted to the live frame may be greatly varied.

It will bereadily understood that a radially unbalanced rotating shaft is hard on the bearings. Unequal wear upon the bearings is minimized by having the bearings free to rotate. In the present instance, the bearings 38 and 39 as a whole, rotate freely in inner and outer races 51 and 52.

The outer races 52 are annular rings having outwardly extending flanges 53 which overlap the side plates of the vibratory head and are fixed thereto by bolts'through the holes 54, so that the races 52 are permanently installed. They have each an inwardly directed flange 55 forming the inner retaining wall of the raceway for the bearing. A ring 56'is bolted to the race 52, having an inwardly directed overlapping flange 57 which forms the outer retainingwall of the raceway, The inner races 5 are formed as bushings fitting the ends of the shafts 4 and i1. Said ends are of reduced diameter, a shoulder being formed about said ends in the diametrical planes bounding theends of the unbalancedvweights, and the 4 inner races 51 have outturned flanges 58 that freely contact said shoulders at both ends of the shafts, preventing endwise movement of the shafts. Said flanges form the inner retaining walls of the raceways for the inner bearings, and are thicker than the corresponding flanges 55 of the outer races so as to set the weights 45 and 46 slightly away from the flanges 55 at both sides of the vibratory head. The inner races 52 have no outer hearing retaining flanges. At the side of the vibratory head adjacent the gears 42 and 43 the tapered bushings 48 hold the inner races against endwise movement in an outward direction, while the gears themselves have hub flanges 59 that form the outer walls of the raceways of the inner races.

On the Opp site sides of the vibratory head the inner race for the bearing of the shaft 40 is held against outward endwise movement by a push plate 60, secured by a bolt 61 to the adjacentendof theshaft 40.

The gears and bearings 'on one side of-the vibratory head and the hearings on the other side are protected by being enclosed in respective removable covers 62 and 63, bolted to the respective side plates 36 and 37. The end of the shaft 41 which carries the'driving pulley 44 is elongated so that it extends through the cover 63 with the pulley on the outside. The inner bearing vrace 51 which surrounds this. end of the shaft is also elongated .so as to pass through the cover 63, andv has its outer portion supported by a bearing 64 secured to the cover 63. Said bearingforms an' oil seal for the adjacent end of said shaft. In fact, it is the sole oil seal associated with the vibratory head.

Although the free rotatability of the bearings 38 and 39 within their respective raceways equali zes. the wear upon the bearings, the unbalanced stresses created by the rotation of the eccentric weights causes the excessive wear so that the bearings 38 and 39 must from time. to time be renewed. This is readily done afterthe covers 62 and .63 and the pulley 44 have been removed, simply by removing the rings 57 at both sides of the vibratory head'as well as the gears 42 and 43, whereupon, the bearings are free and may be slipped out endwisell Now, reverting to the vibration control member which has been previously described, the rubber bumper block 17 bears against a face plate 65 carried by the livef rarne. The pressure with whichfit bears may be adjustably varied by screwing the bolt 14 in or out; The pressure should be such that the block 19 does notjmove relative V to the face plate within the normal vibratory range of the unit, but moves with it, remaining in contact withthe same spot of the face plate. This is made possible through the fact that the bumper block for the greater portion of its length is free to bend in the free space which surrounds it.

At stopping or starting, when the unit is slowing down or picking up speed, the amplitudeof the vibrations is excessive, since the interval between vibration peaks is sufficient to let the supporting springs 23 vibrate throughout a great part of their range of amplitude. This causes a very violent bouncing action of the live frame upon the supporting springs. At such times, the bumper 'block cannot 'keep moving with the faceplate, since invits bending movements it encounters the edge of the surrounding cup near the free end of theLblock. The result is that beyond the normal range of vibration amplitude for which the vibration control member is desired, the rubber block frictionally slidesagainst the face plate dampening the excessive vibrations.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of the invention, it will, be understood by those skilled in the art that the specific details of construction and arany direction, thanks to rangement of parts, as shown and described, are by way of example. and not to .be construed as limiting scope of the invention.

What I claim is:

1. A vibratory screen assembly comprising a fixed frame and a vibratory frame including a screen, spring mounts between said fixed and vibratory frame at plural points, being the sole support of said vibratory frame, means for imparting vibration to said vibratory frame which may vary in amplitude, means for automatically dampening vibrations beyond the normal range of amplitude without affecting vibrations within the normal range, comprising a rigid socket member mounted on said fixed frame, a rubber block Within said socket member seated against the base thereof and extending beyond its month end into contact with a planiform surface on said vibratory frame, means for adjustably pressing said block into sticking contact with said surface, there being substantial clearance between said block and socket member throughout the major portion of the length of said block to permit elastic bending of said block without inhibition by the surrounding socket member, responsive to vibrations within the normal amplitude range, the movement of said block being inhibited by contact with the mouth edge of said socket member responsive to vibrations beyond the normal amplitude range creating frictional slippage between said block and said planiform surface, with braking effort. a

2. A vibratory classification apparatus comprising a fixed frame and a vibratory classifying frame, spring mounts between said fixed and vibratory frames at plural points, being the sole support of said vibratory frame, means for imparting vibration to said vibratory frame which may vary in amplitude, means for automatically dampening vibrations beyond a determined normal range of amplitude without affecting vibrations within the normal range, comprising a rigid socket member mounted on said fixed frame, a block of rubber-like material Within said socket member seated against the base thereof and extending beyond its mouth end into contact with a planiform surface on said vibratory frame, means for holding said block pressed into sticking contact with said surface, there being substantial clearance between said block and socket member throughout the major portion of the length of said block to permit elastic bending of said block without inhibition by the surrounding socket member responsive to vibrations within the normal amplitude range, the movement of said block being inhibited, by contact with the mouth edge of said socket member responsive to vibrations beyond the normal amplitude range, creating frictional slippage'between said block and said planiform surface, with braking effect.

3. A vibratory classification apparatus as claimed in claim 2, including means for adjustably varying the pressure of said block against said surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,312,477 PollitZ Mar. 2, 1943 2,445,175 Hittson July 13, 1948 2,574,773 Bannister Nov. 13, 1951 FOREIGN PATENTS 1,017,071 France Sept. 10, 1952 

